Here's a little bit more elaboration on the problem of coastlines in Mapnik. This information can be found at the OSM Wiki: http://wiki.openstreetmap.org/wiki/Coastline
Unlike every other feature in the OSM database, coastlines are rendered differently in Mapnik. The Mapnik rendering software needs closed polygons to render areas, and since coastlines are the largest and most basic polygons there is on any map, OSM has to ensure that it feeds Mapnik closed coastlines in order to coherently show seas and islands. For zoom levels 0-9, OSM ignores all coaslines data in OSM and uses the public domain VMAP0 data. For zoom levels higher than 9, OSM uses the Coastline error checker tool < http://wiki.openstreetmap.org/wiki/Coastline_error_checker> to generate closed shapefiles that Mapnik can use. This tool is only run infrequently and that is why coastlines do not update often in Mapnik. On Thu, Jul 15, 2010 at 1:48 PM, maning sambale <emmanuel.samb...@gmail.com>wrote: > On Thu, Jul 15, 2010 at 1:41 PM, Jim Morgan <j...@datalude.com> wrote: > > maning sambale wrote, On Thursday, 15 July, 2010 12:01 PM: > >> What I mean here is the mainland of Palawan. But yes the smaller > >> islands needs more work. > > > > Hmmm, now I'm beginning to think I didn't understand. I thought you were > saying that the coastline of Palawan (yes, the main island) was 99% free of > jagged coastlines. But when I look at it I can see about 30% unjagged, and > 70% jagged. eg > > > > < > http://www.openstreetmap.org/?lat=9.1627&lon=118.2309&zoom=13&layers=B000FTF > > > > > > Am I looking at the wrong thing here? Do you have a different view with > all the jaggies removed? Ah ... or maybe I'm looking at the OSM rendered > map, which hasn't been updated. Is that it? In which case, sorry to be dumb. > Try the osmarender layer > > http://osm.org/go/4nECSgr?layers=0B00FTF > > Mapnik coastlines doesn't update too often. > > > > Jim > > > > -- > > datalude: information security > > e: j...@datalude.com > > Philippines: +63 2 403 1311 / mob: +63 920 912 5830 > > Hong Kong: +852 6840 6693 > > w: http://www.datalude.com/ > > > > > > -- > cheers, > maning >
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